1. Field of the Invention
The present invention relates to a drain discharge apparatus capable of smoothly discharging the drain accumulated in a fluid pressure circuit to the outside.
2. Description of the Related Art
A drain discharge apparatus has been hitherto used, for example, in order that the drain, which is accumulated in a fluid pressure circuit, is discharged to the outside. As shown in FIGS. 9 and 10, the drain discharge apparatus 1 concerning such a conventional technique comprises a bowel 3 which is surrounded by a cover member 2. A drain cock 5, which has a drain discharge port 4, is installed to a bottom surface portion of the bowel 3.
Those arranged in the bowel 3 include a float 6 which is floated by the drain stored in the bowel 3, and a first valve member 9 which is operated such that a plate-shaped valve plug 7 is separated from a seat section 8 to give the valve-open state when the float 6 is floated. A support member 10 is arranged in the internal space of the float 6. An annular screen 12, through which the drain is allowed to pass, is provided on a lower end side of the support member 10.
Those arranged in the bowel 3 further include a piston 14 which is urged downwardly in accordance with the action of the resilient force of a spring member 13 and which is displaceable along the inner wall surface of the support member 10, and a second valve member 16 which is constructed by a piston packing 15 for seating the piston 14 thereon.
A filter 17 is installed to a central portion of the piston 14. A bleed passage 18, which makes penetration in the axial direction, is formed at the inside of the piston 14.
In the ordinary state shown in FIG. 9, the air having a predetermined pressure is charged in the bowel 3, giving a situation in which the piston 14 overcomes the resilient force of the spring member 13 owing to the pressure of the air, and the piston 14 is displaced upwardly.
The operation of the drain discharge apparatus 1 concerning the conventional technique will be briefly explained. Starting from the initial position shown in FIG. 9, when the float 6 is floated in accordance with the action of the drain stored in the bowel 3, then the valve plug 7 is displaced integrally with the float 6, and thus it is separated from the seat section 8. Accordingly, the first valve member 9 is in the valve-open state. Therefore, the air, which is introduced through the opening of the seat section 8, flows to the side over the piston 14, i.e., to the internal space of the support member 10, and it presses the piston 14 downwardly. The piston 14 is pushed and moved downwardly in accordance with the pressing force of the air and the resilient force of the spring member 13. Accordingly, the piston 14 is separated from the piston packing 15, and the second valve member 16 is in the valve-open state. As a result, as shown in FIG. 10, the drain, which has passed through the screen 12, passes through the gap between the piston packing 15 and the piston 14, and it is discharged to the outside from the drain discharge port 4.
The float 6 is moved downwardly as the drain is discharged. The valve member 7 is seated on the seat section 8, and thus the first valve member 9 is in the valve-closed state. In this arrangement, the air, which remains on the side over the piston 14, is exhausted to the outside via the bleed passage 18. The piston 14 is pushed and moved upwardly by the air in the bowel 3, and it is restored to the initial position shown in FIG. 9.
When the air in the bowel 3 is exhausted, the air pressure to push and move the piston 14 upwardly disappears. Therefore, the piston 14 is displaced downwardly in accordance with the resilient force of the spring member 13, and the second valve member 16 is in the valve-closed state. As a result, the drain, which has passed through the screen 12, passes through the gap between the piston packing 15 and the piston 14, and it is discharged to the outside from the drain discharge port 4.
However, the drain discharge apparatus 1 concerning the conventional technique described above involves such an inconvenience that the structure of the entire apparatus is complicated, a large number of parts are required, and the production cost is expensive.
The drain discharge apparatus 1 concerning the conventional technique adopts the following arrangement. That is, when the drain is discharged, the air is always exhausted to the outside via the orifice of the seat section 8, the filter 17, the bleed passage 18, and the drain discharge port 4. Therefore, an inconvenience arises in that the air is wasted.
Further, in the case of the drain discharge apparatus 1 concerning the conventional technique, when the air is newly supplied to the inside of the bowel 3 after the air in the bowel 3 is exhausted to the outside, then the piston 14 is located at the downward position due to the resilient force of the spring member 13, and the second valve member 16 is in the valve-open state. For this reason, the air in the bowel 3 passes through the screen 12 and the gap between the piston packing 15 and the piston 14 respectively, and it is discharged to the outside from the drain discharge port 4, until the air arrives at an air pressure which is required to displace the piston 14 upwardly against the resilient force of the spring member 13. Therefore, the drain discharge apparatus 1 concerning the conventional technique involves an inconvenience that the air is wasted, also from this viewpoint.